The main purpose of our project is to relate intraspecific aggresion induced by "thwarting" or extinction-type procedures with intraspecific aggression that accompanies reproduction in the same species. Attack motor patterns and the role of visual target features including, conspecific target posture, size, movement and removal will be examined in both feral and domestic birds (pigeons and quail) under both attack-inducing situations. BIBLIOGRAPHIC REFERENCES: Cohen, P.S., Yoburn, B. and Looney, T.H., An inexpensive random access projector for rapid presentation of pictorial images. Journal of the Experimental Analysis of Behavior, in press. Looney, T.H., Cohen, P.S. and Yoburn, B., Variables affecting Establishment of Schedule-induced attack of pictorial targets in White King pigeons, Journal of the Experimental Analysis of Behavior, in press..